Here are some links for a couple of your problems...

Reference the hanging indentation, margins, etc....

...This has to do with styles/formatting and is addressed at:
http://www.shaunakelly.com/word/numbering/numbering20072010.html.

Reference marking and checking text/grammar, etc....

...This has to do with styles/formatting and is addressed at:
http://www.shaunakelly.com/word/numbering/numbering20072010.html.
Yes, repeated on purpose. Why? Because, if your document is properly formatted (instead of all text using the same style [i.e., “Normal”]), your highlighting will only apply to that “style” and not the whole document.

The referenced links are for MSWord 2010. Other links are available for other versions.

EDIT: I did not read down far enough. Here is your quote: "but since I only ever use the one style, it does not seem very relevant. I accept that I probably should understand them better: one day".

To that quote, if you are only going to use one style, you will ALWAYS have the problems you describe. So, your "one day" should be pretty soon if you want to overcome these apparent frustrations. :>)